Merge tag 'for-v5.7' of git://git.kernel.org/pub/scm/linux/kernel/git/sre/linux-power...
[linux-2.6-microblaze.git] / tools / perf / bench / futex-requeue.c
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Copyright (C) 2013  Davidlohr Bueso <davidlohr@hp.com>
4  *
5  * futex-requeue: Block a bunch of threads on futex1 and requeue them
6  *                on futex2, N at a time.
7  *
8  * This program is particularly useful to measure the latency of nthread
9  * requeues without waking up any tasks -- thus mimicking a regular futex_wait.
10  */
11
12 /* For the CLR_() macros */
13 #include <string.h>
14 #include <pthread.h>
15
16 #include <signal.h>
17 #include "../util/stat.h"
18 #include <subcmd/parse-options.h>
19 #include <linux/compiler.h>
20 #include <linux/kernel.h>
21 #include <linux/time64.h>
22 #include <errno.h>
23 #include <internal/cpumap.h>
24 #include <perf/cpumap.h>
25 #include "bench.h"
26 #include "futex.h"
27
28 #include <err.h>
29 #include <stdlib.h>
30 #include <sys/time.h>
31
32 static u_int32_t futex1 = 0, futex2 = 0;
33
34 /*
35  * How many tasks to requeue at a time.
36  * Default to 1 in order to make the kernel work more.
37  */
38 static unsigned int nrequeue = 1;
39
40 static pthread_t *worker;
41 static bool done = false, silent = false, fshared = false;
42 static pthread_mutex_t thread_lock;
43 static pthread_cond_t thread_parent, thread_worker;
44 static struct stats requeuetime_stats, requeued_stats;
45 static unsigned int threads_starting, nthreads = 0;
46 static int futex_flag = 0;
47
48 static const struct option options[] = {
49         OPT_UINTEGER('t', "threads",  &nthreads, "Specify amount of threads"),
50         OPT_UINTEGER('q', "nrequeue", &nrequeue, "Specify amount of threads to requeue at once"),
51         OPT_BOOLEAN( 's', "silent",   &silent,   "Silent mode: do not display data/details"),
52         OPT_BOOLEAN( 'S', "shared",   &fshared,  "Use shared futexes instead of private ones"),
53         OPT_END()
54 };
55
56 static const char * const bench_futex_requeue_usage[] = {
57         "perf bench futex requeue <options>",
58         NULL
59 };
60
61 static void print_summary(void)
62 {
63         double requeuetime_avg = avg_stats(&requeuetime_stats);
64         double requeuetime_stddev = stddev_stats(&requeuetime_stats);
65         unsigned int requeued_avg = avg_stats(&requeued_stats);
66
67         printf("Requeued %d of %d threads in %.4f ms (+-%.2f%%)\n",
68                requeued_avg,
69                nthreads,
70                requeuetime_avg / USEC_PER_MSEC,
71                rel_stddev_stats(requeuetime_stddev, requeuetime_avg));
72 }
73
74 static void *workerfn(void *arg __maybe_unused)
75 {
76         pthread_mutex_lock(&thread_lock);
77         threads_starting--;
78         if (!threads_starting)
79                 pthread_cond_signal(&thread_parent);
80         pthread_cond_wait(&thread_worker, &thread_lock);
81         pthread_mutex_unlock(&thread_lock);
82
83         futex_wait(&futex1, 0, NULL, futex_flag);
84         return NULL;
85 }
86
87 static void block_threads(pthread_t *w,
88                           pthread_attr_t thread_attr, struct perf_cpu_map *cpu)
89 {
90         cpu_set_t cpuset;
91         unsigned int i;
92
93         threads_starting = nthreads;
94
95         /* create and block all threads */
96         for (i = 0; i < nthreads; i++) {
97                 CPU_ZERO(&cpuset);
98                 CPU_SET(cpu->map[i % cpu->nr], &cpuset);
99
100                 if (pthread_attr_setaffinity_np(&thread_attr, sizeof(cpu_set_t), &cpuset))
101                         err(EXIT_FAILURE, "pthread_attr_setaffinity_np");
102
103                 if (pthread_create(&w[i], &thread_attr, workerfn, NULL))
104                         err(EXIT_FAILURE, "pthread_create");
105         }
106 }
107
108 static void toggle_done(int sig __maybe_unused,
109                         siginfo_t *info __maybe_unused,
110                         void *uc __maybe_unused)
111 {
112         done = true;
113 }
114
115 int bench_futex_requeue(int argc, const char **argv)
116 {
117         int ret = 0;
118         unsigned int i, j;
119         struct sigaction act;
120         pthread_attr_t thread_attr;
121         struct perf_cpu_map *cpu;
122
123         argc = parse_options(argc, argv, options, bench_futex_requeue_usage, 0);
124         if (argc)
125                 goto err;
126
127         cpu = perf_cpu_map__new(NULL);
128         if (!cpu)
129                 err(EXIT_FAILURE, "cpu_map__new");
130
131         memset(&act, 0, sizeof(act));
132         sigfillset(&act.sa_mask);
133         act.sa_sigaction = toggle_done;
134         sigaction(SIGINT, &act, NULL);
135
136         if (!nthreads)
137                 nthreads = cpu->nr;
138
139         worker = calloc(nthreads, sizeof(*worker));
140         if (!worker)
141                 err(EXIT_FAILURE, "calloc");
142
143         if (!fshared)
144                 futex_flag = FUTEX_PRIVATE_FLAG;
145
146         if (nrequeue > nthreads)
147                 nrequeue = nthreads;
148
149         printf("Run summary [PID %d]: Requeuing %d threads (from [%s] %p to %p), "
150                "%d at a time.\n\n",  getpid(), nthreads,
151                fshared ? "shared":"private", &futex1, &futex2, nrequeue);
152
153         init_stats(&requeued_stats);
154         init_stats(&requeuetime_stats);
155         pthread_attr_init(&thread_attr);
156         pthread_mutex_init(&thread_lock, NULL);
157         pthread_cond_init(&thread_parent, NULL);
158         pthread_cond_init(&thread_worker, NULL);
159
160         for (j = 0; j < bench_repeat && !done; j++) {
161                 unsigned int nrequeued = 0;
162                 struct timeval start, end, runtime;
163
164                 /* create, launch & block all threads */
165                 block_threads(worker, thread_attr, cpu);
166
167                 /* make sure all threads are already blocked */
168                 pthread_mutex_lock(&thread_lock);
169                 while (threads_starting)
170                         pthread_cond_wait(&thread_parent, &thread_lock);
171                 pthread_cond_broadcast(&thread_worker);
172                 pthread_mutex_unlock(&thread_lock);
173
174                 usleep(100000);
175
176                 /* Ok, all threads are patiently blocked, start requeueing */
177                 gettimeofday(&start, NULL);
178                 while (nrequeued < nthreads) {
179                         /*
180                          * Do not wakeup any tasks blocked on futex1, allowing
181                          * us to really measure futex_wait functionality.
182                          */
183                         nrequeued += futex_cmp_requeue(&futex1, 0, &futex2, 0,
184                                                        nrequeue, futex_flag);
185                 }
186
187                 gettimeofday(&end, NULL);
188                 timersub(&end, &start, &runtime);
189
190                 update_stats(&requeued_stats, nrequeued);
191                 update_stats(&requeuetime_stats, runtime.tv_usec);
192
193                 if (!silent) {
194                         printf("[Run %d]: Requeued %d of %d threads in %.4f ms\n",
195                                j + 1, nrequeued, nthreads, runtime.tv_usec / (double)USEC_PER_MSEC);
196                 }
197
198                 /* everybody should be blocked on futex2, wake'em up */
199                 nrequeued = futex_wake(&futex2, nrequeued, futex_flag);
200                 if (nthreads != nrequeued)
201                         warnx("couldn't wakeup all tasks (%d/%d)", nrequeued, nthreads);
202
203                 for (i = 0; i < nthreads; i++) {
204                         ret = pthread_join(worker[i], NULL);
205                         if (ret)
206                                 err(EXIT_FAILURE, "pthread_join");
207                 }
208         }
209
210         /* cleanup & report results */
211         pthread_cond_destroy(&thread_parent);
212         pthread_cond_destroy(&thread_worker);
213         pthread_mutex_destroy(&thread_lock);
214         pthread_attr_destroy(&thread_attr);
215
216         print_summary();
217
218         free(worker);
219         return ret;
220 err:
221         usage_with_options(bench_futex_requeue_usage, options);
222         exit(EXIT_FAILURE);
223 }